Before the last federal election the Coalition promised a customs vessel would be provided to monitor Japan’s Antarctic whale hunt. But once in power their priorities changed and the vessel, the Ocean Protector, is now patrolling Australia’s northern boundaries as part of Operation Sovereign Borders.

To replace the Ocean Protector the government chartered a plane budgeted to fly just three times during the three months of Japan’s Southern Ocean whale hunt, which is now drawing to a close for the year. This year, the job was left entirely up to Sea Shepherd.

Sea Shepherd’s goal in the Southern Ocean is to secure the slipway of the Nisshin Maru — a Japanese vessel which functions as a giant floating abattoir — in a sort of high seas sit-in. The Nisshin Maru is accompanied by three harpoon vessels (Yushin Maru No. 1, 2 and 3) and a Japanese Government security vessel (Shonan Maru No. 2). When the stern of the factory ship is blocked, the harpoon ships can’t offload their kills and therefore can’t whale further.

The fleet sails to Antarctica each summer aiming to kill 1035 minke, humpback and fin whales in an internationally recognised whale sanctuary.

This year I was a quartermaster on the long-range Sea Shepherd vessel, the Bob Barker. During the summer we pursued the whaling fleet, trying to first locate, then disrupt their convoy.

The first skirmish with the whalers came a month after we located them for the second time. We had been sitting on the factory ship’s slipway for eight days without incident when the harpoon vessels launched a prolonged and unprovoked assault.

The whalers had timed their first offensive with a low-pressure system that swept in earlier that day. The icy wind churned up the waters at the opening to the Ross Sea, south of New Zealand.

Sea Shepherd’s flagship vessel, the Steve Irwin, and the Bob Barker, were running on a parallel course about a quarter of a mile off the factory ship’s stern. A transmission came over the radio from the Yushin Maru informing us the harpoon ships would begin trailing lines if we didn’t change our course.

The Yushin Maru manoeuvred in between the two Sea Shepherd ships crossing in front of the Steve Irwin’s bow, trailing hundreds of metres of steel cable, in the first of over 86 such assaults. The harpoon ships weaved in and around us in formation. To avoid damage to our propellers, the Sea Shepherd ships were forced to continuously evade the lines and circle back around. The Nisshin Maru began to fade into the fog on the horizon.

On one approach the Yushin Maru No. 3 cut too close to the Bob Barker and a collision was inevitable. “Hold on!” yelled Captain Peter Hammarstedt as the Yushin No. 3 slammed into us at high speed. The whole ship shuddered with the impact.

For 10 hours the assault raged and eventually the Nisshin disappeared off our radar, heading due north. At the tail end of the melee, the Steve was miles away. The harpoon ships were still circling and showed no signs of abating. We were barely able to make any ground before they were on our beam again ready for another cross.

The Institute for Cetacean Research (ICR), the charter who own the Japanese whaling fleet, put out a press release the next day claiming Sea Shepherd attacked the whaling vessels.

“The Bob Barker approached abnormally close to the Yushin No. 3 colliding with her stern.”

Twenty-two days after our first battle with the whaling fleet we located the Nisshin Maru again. We chased them north for hours before the harpoon ships moved into place for their second attack just before nightfall.

“Bob Barker, Bob Barker, this is the Yushin Maru, Yushin Maru Number 3. Warning. Keep clear. Avoid collision,” came a transmission from the Yushin Maru Number 3.

“Immediately alter course and keep a safety [sic] distance.” At the time of the call we were six nautical miles away from the Nisshin Maru.

This time we were better prepared for the attack. The harpoon ships crossed our bow a total of 33 times, in violation of International Collision Regulations at sea. The whalers threw projectiles at our small boat crew and shone powerful lights into our bridge making it difficult to navigate.

Sea Shepherd fired flares to warn the whalers to keep their distance as we launched the small boats which trailed defensive lines to deter the harpoon ships from crossing our bow.

After six hours the Nisshin Maru disappeared off our radar. The ICR again accused Sea Shepherd of being the aggressor.

Within a week the same story played out again, except this time the harpoon vessels attacked before we even had the factory ship on our radar. We were 36 nautical miles away from the Nisshin Maru when the harpoon ships began trailing cable in front of us.

The ICR statement said: “During the Sea Shepherd attacks the YS1 and the YS3 sent prior warnings to the BB requesting it not to close in due to danger of collision and as a safety measure, started towing a warning buoy wire.”

Sea Shepherd attempted to push the issue onto the Australian Government’s agenda, pressuring Australia to lodge a diplomatic protest with Japan on behalf of the 30-odd Australians on board the three Sea Shepherd ships.

Trade minister, Andrew Robb, made clear that a Free Trade Agreement with Japan was more important than defending the Southern Ocean Whale Sanctuary from plunder.

“[The Coalition] is just as concerned about whaling as the other side [Labor], but it’s all about where priorities lie in terms of how we deal with that,” Robb said. “Our priority in coming to government is to fix the economic mess we have inherited, so we are focusing on those things that will create jobs in Australia.”

This year’s campaign has come to an end. Antarctica will soon go back into a deep freeze and the ice is already closing around the Ross Sea, forming a barrier that will protect this wild and beautiful place from human exploitation for the winter.

The whales are migrating north and will soon be passing the Australian coastline. And the whalers are heading north for the winter too, with a dramatically reduced catch.

Despite our successes, the Ocean Protector’s presence in the Southern Ocean would have been a game-changer. The whaling fleet would have been much more hesitant to launch the brazen attacks that characterised the campaign and Sea Shepherd would have been able to maintain their position on the slipway of the Nisshin Maru. That would have meant more whales could have been saved.